This invention relates to a process and apparatus for manufacturing a blowable glass fiber thermal insulation product. The invention also relates to the product itself produced by the process and apparatus. The concept disclosed generally involves the manufacture of a blowable glass fiber thermal insulation product from unbonded glass fiber matting and lengths of twisted glass fiber yarn. The glass fiber matting and yarn are processed in such a way as to result in a relatively low density, high thermal resistance value product in a loose form suitable for blowing into building walls and other cavities.
Thermal insulations are those materials or combinations of materials which, when properly applied, retard the flow of heat energy by conductive, convective and radiative transfer. These thermal insulation materials may be fibrous, particulate, film or sheet, block or monolithic, open or closed cell, or composites thereof which may, in addition, have chemical or mechanical bonding or support.
By retarding heat flow, thermal insulation can conserve insulation by reducing heat loss or gain from piping, ducts, vessels, equipment and building structures; control surface temperatures of equipment and structures for personnel protection and comfort; facilitate temperature control of a chemical process, a piece of equipment or a structure; prevent vapor condensation at surfaces having a temperature below the dew point of the surrounding atmosphere; or reduce temperature fluctuations within an enclosure when heating or cooling is not needed or not available.
Thermal insulations may also impede water vapor transmission, prevent or reduce damage to equipment and structures from exposure to fire or freezing conditions and reduce noise and vibration.
Thermal insulations normally comprise mineral, fibrous or cellular materials, organic fibrous or cellular materials, or metallic or metallized organic reflective membranes. The disclosure of this application relates specifically to fiberglass, a mineral fiber having low heat transfer properties ideal for insulation purposes. Fiberglass insulation is usually formed into batts which are sold in rolls and which are unrolled to cover the area to be insulated. In contrast, the product according to the present invention comprises clumps or nodules of fiberglass which are blown into walls or other enclosed spaces.
Because the raw materials for the product according to this invention are usually waste or scrap, the insulation can be manufactured very inexpensively. The properties of the raw materials, as described below, permit a very efficient blowable insulation to be simply and easily manufactured according to the process and apparatus also disclosed in this application.
Another characteristic of the product lies in its ability to be greatly compressed and shipped in relatively small volume containers. Because the insulation is not bound together by a bonding agent or an adhesive, the insulation is lighter in weight, does not need to be shredded before insulation, covers the insulation space more evenly and avoids packing down under its own weight.
One form of prior art insulation material is disclosed in the Bemis et al. Pat. No. 4,296,164. This blowable fiberglass thermal insulation is made by slitting and cross-cutting a blanket of fibrous glass wool into rectangular chunks and conveying the chunks to a bagging machine. As disclosed in the Bemis application, the insulation is first made by melting glass to form veils of glass fibers which are collected on a conveyor to form a fibrous glass blanket. A thermo-setting binder is then applied to the blanket to set the fibers in a particular arrangement. The binder is cured. Then the slitting and cross-cutting of the blanket takes place to form chunks of fibers which then break into smaller chunks at random during subsequent processing.
Another known prior art process involves grinding fiberglass into small pieces which are then sprayed with an adhesive. The fiberglass is then compressed very tightly into a container for shipment. The fiberglass "blooms" into a product of suitable density for insulation when the insulation is removed from its container. However, the product is still in one large piece because of the adhesive, making it necessary for the installer to process the product through a shredder to break the fiberglass into small pieces suitable for use with a blower.
In the product according to the present invention, these difficulties are circumvented by avoiding the use of any type of binder or adhesive.